The effect of chilling on membrane lipid phase transition in human oocytes and zygotes

Yehudith Ghetler, Saar Yavin, Ruth Shalgi, Amir Arav

Research output: Contribution to journalArticlepeer-review


Background: Chilling injury occurs when the cell membrane undergoes a transition from the liquid state to the gel state. Human oocytes and single-cell zygotes are of similar shape and size but the post-thawing survival rate of oocytes is poorer. We set out to investigate the possible difference in membrane lipid phase transition (LPT) temperature between the two cell types. Methods: The LPT temperature was measured with a Fourier Transform Infrared analyser, which detects the change in the vibration frequency of the CH2 bond stretches of the membrane lipid molecules during temperature change. The LPT temperatures of unfertilized human oocytes, in vitro-matured oocytes, and immature germinal vesicle (GV) stage oocytes were compared with that of abnormally fertilized human zygotes. Results: The LPT temperatures of zygotes and of mature and immature GV oocytes differ significantly from each other (10.0 ± 1.2, 16.9 ± 0.9 and 24.4 ± 1.6°C respectively; P < 0.05). Conclusions: Zygotes show a higher resistance to chilling injury compared to oocytes at different developmental stages; this might explain the relatively poor survival rates of cryopreserved human oocytes and indicates the necessity to adjust the cryopreservation protocols in order to minimize cryoinjury.

Original languageEnglish
Pages (from-to)3385-3389
Number of pages5
JournalHuman Reproduction
Issue number12
StatePublished - Dec 2005


  • Chilling injury
  • Cryopreservation
  • Human oocyte
  • Human zygote
  • Lipid phase transition


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